Horse people in the USA know pergolide (also called Permax, when the brand name is used) as the medication of choice for many horses suffering from Cushing's disease. What many in the horse world don't know is that it is actually a human medication used to treat symptoms of Parkinson's disease.
Recently, reports have surfaced of heart problems developing in human patients. Acting on those reports, the FDA today announced that the drug--both Permax and pergolide generic derivatives--will no longer be sold in the US.
What does that mean to owners of horses with Cushing's disease? It's hard to say. I have been trying to get more information to share.
As always, Eleanor Kellon VMD is right on the case. Dr Kellon is veterinary consultant to the Equine Cushings discussion list on yahoo.com; the list currently boasts almost 5000 members, of which I am one, and the group is one of the fairest, best-informed and most diligent that I have found on the web. Obviously many of those 5000 are medicating their horses with pergolide and this is Big News on the List today.
Here is some sage advice from Dr Kellon: "First, don't panic.Many drugs that fall by the wayside for human use actually end up in veterinary use. Trental (pentoxifylline) is a good example. They're not approved for veterinary use, but the FDA grants veterinarians considerable leeway in 'off-label' (i.e. not approved for the use on
the label) drug prescribing in animals.
"There may be some information available on closely related alternatives," she continued. "I'm checking into that."
"In humans, most recent studies are finding about 22% of people on pergolide develop some level of dysfunction of their heart valves. The number that develop serious problems with it is much, much lower. As for horses **as far as we know, the has not been recognized as a clinical problem in horses on pergolide**. We probably have more
long term follow up on Cushing's horses here than even in university vet school records. Some horses here have been on it for 5, even 10 years."
Dr.Kellon is also the author of the reference book Equine Drugs and Vaccines, as well as Equine Supplements and Nutraceuticals, both of which are well-thumbed and never far from my desk.